When creating a model with BPMN.IO, an initiator can be linked to a StartEvent. I am using the Camunda REST API to start processes from a C# environment.Is there a way to start the corresponding deployed process without the use of a database that stores the connection between the Initiator and the ProcessID?

It is not clear to me what you want to achieve. What I think I understand: You want to use the camunda:initiator attribute, yet you don't want historic process instances linked to that user (via #getStartUser()). If that is correct, why would you use camunda:initiator then? Or is this more a question whether processes can be executed without a database?

There is an existing application, I would like to implement Camunda to manage custom processes. The main point is that clients will be able to model their own processes.

Say, for example, a client wants to make a custom process for handling a new registration. He models a process with a StartEvent. The camunda:initiator value of this StartEvent would now be "RegistrationCreated".

In the existing application, executing the functionality of a new registration should of course trigger/create an instance of the custom process. It would make sense if there was a call to the REST-API that tells it that a certain event has occured, and the processes linked to this event would initiate.

I had the idea that the camunda:initiator had this purpose, as in WHAT initiates the process. But i think it is meant for WHO initiates it. My apologies for this misunderstanding, im quite new to Camunda.

So, that brings me to the question, how can i trigger a process by telling the REST-API that an event has occured? This would allow me to make standard REST-calls in existing methods to initiate the corresponding processes.

But, another question pops up now. When starting a process, the variables declared in it are to be initated too. How do i know which variables i need to initiate without hardcoding it?